The invention relates to a device and method for transporting viscous and thermally sensitive fluids through a pipeline.
The use of pressure relief devices is generally known. Conventional means comprise valves or rupture discs for example. Pressure relief valves protect pressurised rooms or pressure containers from an impermissible pressure rise, which may lead to damage of the connected pressure equipment. Valves drain gases, vapours or liquids into the atmosphere or into collection pipes if the response pressure is exceeded. Rupture discs have a membrane, which burst under the action of a pressure that is higher than normal operating pressure but lower than the pressure that would break a pipe or vessel itself, as a result of which a pressure relief is enabled with an exterior space. Pressure relief devices lead to a local reduction of the system pressure under the previously mentioned conditions. Pressure relief apparatuses can only be attached in a limited manner due to the geometry of e.g. pipes or channels.
Rupture discs themselves furthermore have design and production limitations as pressure relief apparatus. So, rupture discs cannot be formed to be arbitrarily thin or thick, in order to be able to contribute as a device to precise overpressure and underpressure safeguarding. Thus, the response pressure must be sufficiently high in the case of overpressure or low in the case of underpressure. Apparatuses for pressure relief can therefore be divided according to the application possibilities thereof and must always be focussed with reference to the overall system to be safeguarded, and can therefore consist of reusable, non-reusable constituents and custom components, so the selection must take account of many criteria. In addition to the criterion of the pressure, underpressure and installation location of the pressure relief apparatus, the physical-chemical behaviour, such as if appropriate corrosion or abrasion and also the inertial system of the pressure relief must be taken into account. For some processes, pressure relief systems, which are free of dead space, are sought, as reaction products with relatively long dwell times, caused by dead zones, can substantially negatively influence the quality of the products produced. Apparatuses and machines that do not tolerate any dead zones in the plant system are required in the pharmaceutical sector especially.
EP 789 822 relates to a pressure safety device for thermally unstable viscous compounds, such as cellulose, water, NMMO (N-methylmorpholine N-oxide) solutions, in which a burst element penetrates into the interior of a transport pipe.
Pressure relief valves are known for example from U.S. Pat. No. 4,724,857, U.S. Pat. No. 5,067,511 and U.S. Pat. No. 5,577,523. These valves are fittings that can be screwed onto pressure containers for safeguarding, in order to provide corresponding safety devices for undesired pressures.
Thus, U.S. Pat. No. 4,724,857 describes a valve body that can be connected via threaded connections to a plant system for pressure relief. The disadvantage of this pressure relief is the fact that a congested space or dead space within the valve body and upstream of the pressure relief valve body and no through-flow of the space may result. Thus, so-called “dead water zones” may be formed, which on the one hand can block the valve body and on the other hand can impair the pressure relief as a result.
US patent specification U.S. Pat. No. 5,067,511 teaches that the valve body required for pressure relief is fastened on a buckling rod, but the valve body provided for the pressure relief is set so far back in the valve housing, that pronounced dead water zones may be formed.
A fitting is presented in U.S. Pat. No. 5,577,523, which does not release the pipe cross section, owing to a step-by-step opening. Here also, one can see that the medium accumulates upstream of the valve body and a dead water zone is formed. When transporting viscous and thermally unstable or thermally sensitive compounds, particularly those that are only kept fluid by means of heating and tend to form clumps or lead to deposits when cooling, it was a goal, e.g. of EP 789 822 and U.S. Pat. No. 5,337,776, to avoid spaces set back from a pipe, in which these compounds may be deposited. This goal was also pursued in EP 789 822.
JP 2003 093536 A (abstract) relates to a device with a closed mediation cavity for an extinguishing pump without a drain pipeline.
U.S. Pat. No. 6,425,410 B1 shows a shut-off valve of a pipeline, in which a closable shut-off disc is connected to a buckling rod. During normal operation, the pipeline is closed and is opened in the event of pressure against the bolt, wherein the pressure is mediated above the upper part of the shut-off disc.
U.S. Pat. No. 5,297,575 A describes a similar shut-off valve to that shown in U.S. Pat. No. 6,425,410 B1. A piston is used therein instead of a shut-off disc.
JP 2007 232178 A (abstract) describes a device for an extinguishing hose with a rupture disc. The rupture disc is not rinsed by a fluid pumped through a pipe. Furthermore, the rupture disc is not a displaceable sealing component, but rather a component which breaks open under pressure and thereby forms an opening.
U.S. Pat. No. 5,337,776 teaches that the rupture disc, installed in a pipe, should be realised in such a manner that the rupture membrane sits flush in the wall of the pipe. For this purpose, the pipe according to U.S. Pat. No. 5,337,776 must be designed and structured in such a manner that the continuous compound pipe and also the thermostatic jacket of the pipe must be interrupted and thus an inhomogeneous thermostatting zone is present in the pipe. A further significant disadvantage of U.S. Pat. No. 5,337,776 lies in the fact that the rupture disc described in the patent specification unavoidably has to be welded onto a cylindrical support body. The flush fixing of the rupture disc in the interior of a pipe or in the pipe wall is complex and requires the welding of the rupture disc by means of the electron beam welding method. In addition, it is not possible to use a commercially available rupture disc. Furthermore, the intended goal of total freedom from dead space is not achieved, as the flat rupture discs and the fixings thereof protrude into the curved pipe interior and leave behind non-fluid rinsed regions on the outflow side.